The present invention generally relates to a process and apparatus for retaining conductive pins in pin holes of a spreader plate adapted for thermal transfer. More particularly, the present invention relates to a process for creating retention members about the pin holes to retain the conductive pins within a variable gap interface between the spreader plate and an electronic component.
Electronic devices such as computers contain numerous circuit boards. Each circuit board generally has other electronic components, such as silicon microprocessor chips, mounted and electrically connected thereto. Often the electronic components are connected to the circuit board at an angle to the circuit board such that a top surface of the electronic component is also oriented at an angle to the circuit board. Additionally, the top surfaces of the electronic components may have contours or depressions such that the top surface is not flat or continuous. During operation, the electronic components generate a substantial amount of heat as electrical signals are sent between the electronic components and the circuit board. Typically, heat sinks are connected to the electronic components to absorb and dissipate the heat created by the electronic component. Because the electronic component may have an angled or variably interrupted top surface, most heat sinks do not uniformly contact the electronic component. Hence, the heat sinks do not absorb heat from the electronic component as efficiently as possible when directly connected to the electronic component.
In the past, a thermally conductive coating containing grease and any one of ceramic, boron or aluminum has been applied to the top surface of an electronic component and covered with a compliant pad. The compliant pad is then covered with additional thermally conductive coating and a heat sink is then positioned on top of the compliant pad. The thermally conductive coating and the compliant pad engage the contours, depressions, and angles of the top surface of the electronic component and conduct heat from the electronic component through the compliant pad to the heat sink.
However, the thermally conductive coating and compliant pad suffer from several drawbacks. First, though the thermally conductive coating is more conductive than air, it is not an overly efficient substance for conducting heat from the electronic component to the heat sink. Additionally, the compliant pad is thick and therefore does not efficiently conduct heat.
Recently, a metal thermal transfer intermediary for use between the electronic component and the heat sink has been proposed using a metal spreader plate and a metal variable gap interface (VGI). The spreader plate has a front surface that retains at least one variable gap interface and a flat uninterrupted rear surface. The variable gap interface has a metal base with an array of pin holes. A spring sits in the bottom of each pin hole and supports a metal cylindrical pin such that a portion of the pin extends out of a mouth of the pin hole. The pin may be pushed downward further into the pin hole with the spring being compressed between the pin and the bottom of the pin hole.
In operation, the pins, metal base, and the interior of the pin holes are covered with a thin layer of the thermal conductive coating. The spreader plate is then inverted and positioned on top of the electronic component such that the pins engage and rest on the top surface of the electronic component. The pins support the spreader plate and are pushed into the pin holes. Groups of pins are located within regions of the spreader plate to engage portions of the top surface of the electronic component that may have a different angle, contour, or depth. Thus, the use of several pins allows for the variable gap interface to engage much of the top surface of the electronic component despite the variable topographical features of the top surface. The rear surface of the spreader plate is then covered with a layer of the thermal conductive coating and the heat sink is then positioned on top of the rear surface of the spreader plate.
Heat is conducted from the top surface of the electronic component to the pins, which in turn conduct the heat through the spring and the metal base through the rear surface of the spreader plate to the heat sink. The use of the retractable metal pins held in a metal base and metal spreader plate efficiently conducts the heat from the electronic component to the heat sink. Additionally, the thermally conductive coating fills in air gaps between the electronic component, the variable gap interface, the spreader plate, and the heat sink to further enhance the thermal conductivity of the assembly.
However, the variable gap interface suffers from drawbacks as well. In the recently proposed variable gap interface, the pins are loosely positioned within the pin holes and the thermally conductive coating on the top of the pins sticks to the electronic component. Thus, the pins are pulled out of the variable gap interface when the variable gap interface is removed from the electronic component. Additionally, the pins may fall out of the pin holes whenever the spreader plate is inverted for positioning on the electronic component.
A need remains for a variable gap interface that overcomes the above problems and addresses other concerns experienced in the prior art.